Re: [RFC PATCH 01/15] cmpxchg_local() is not signed-value safe, so fix generic atomics
From: Arnd Bergmann
Date: Wed May 18 2016 - 11:30:38 EST
On Wednesday 18 May 2016 16:10:45 David Howells wrote:
> cmpxchg_local() is not signed-value safe because on a 64-bit machine signed
> int arguments to it may be sign-extended to signed long _before_ begin cast
> to unsigned long. This potentially causes comparisons to fail when dealing
> with negative values.
>
> Fix the generic atomic functions that are implemented in terms of cmpxchg()
> to cast their arguments to unsigned int before calling cmpxchg().
>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
>
Isn't the problem you describe something that cmpxchg() could prevent instead?
Arnd